SOMERSET — Police are investigating a Wednesday night armed robbery at the 7-Eleven convenience store located at the corner of Route 6 and Lee’s River Avenue.

A man entered the store just before 10:45 p.m., approached the counter and asked the clerk for a pack of L&M cigarettes. When the clerk looked up after scanning the cigarettes, he saw the customer holding a knife and ordering the clerk to “give me the money,” Somerset police Capt. Stephen Moniz said in a press release.

The suspect reached over the counter, removed all the cash from the register, and ordered the clerk to hand over a carton of cigarettes. The clerk began putting several packs of cigarettes on the counter when another customer entered the store and walked to the rear, unaware that a robbery was happening, police said.

The suspect took the cigarettes and cash, and left the store, heading east toward Lee’s River Avenue. A witness reported later seeing a gray sedan turning right from Harvey Lane onto Lee’s River Avenue southbound, police said.

Several Somerset police officers, as well as Massachusetts State Police troopers, searched the area but did not find the suspect. He is described as a white man, about 5 feet, 10 inches to 6 feet, 2 inches tall, with a medium build and a “well-groomed” beard. He wore a brown baseball cap, long-sleeve shirt and jeans, police said.